In recent years, a display apparatus has acquired higher resolution with requirements toward high image quality. The high-resolution display apparatus sometimes receives relatively low-resolution image data. A picture image of the low-resolution image data is displayed on screens of the high-resolution display apparatus, and is comparatively small. The apparatus sometimes performs expansion processing of an input image.
Heretofore, in the display apparatus, a pixel interpolation technology as image expansion processing is used. The pixel interpolation interpolates a pixel value lacked in an input image by using pixel values around the pixel value, e.g., by using an FIR (Finite Impulse Response) filter.
However, pictures generated by the expansion processing using the pixel interpolation technology are rough around diagonal lines. So-called “jaggy” may become prominent in the image.